Abstract
OBJECTIVE: Evaluate income disparities in receipt of needle biopsy among Medicare beneficiaries and describe the magnitude of this variation across physician peer groups. METHODS: The Surveillance, Epidemiology and End Results (SEER)-Medicare database was queried from 2007-2009. Physician peer groups were constructed. The magnitude of income disparities and the patient-level and physician peer group-level effects were assessed. RESULTS: Among 9770 patients, 65.4% received needle biopsy. Patients with low income (median area-level household income < $33K) were less likely to receive needle biopsy (58.5%) compared to patients with high income (≥ $50K) (68.6%; adjusted odds ratio 0.77; 95% confidence interval (CI) 0.65-0.91). Needle biopsy varied substantially across physician peer groups (interquartile range 43.4-81.9%). The magnitude of the disparity ranged from an odds ratio (OR) of 0.50 (95% CI 0.23-1.07) for low vs. high income patients to 1.27 (95% CI 0.60-2.68). The effect of being treated by a physician peer group that treated mostly low-income patients on receipt of needle biopsy was nearly three times the effect of being a low-income patient. CONCLUSIONS: Needle biopsy continues to be underused and disparities by income exist. The magnitude of this disparity varies substantially across physician peer groups, suggesting that further work is needed to improve quality and reduce inequities.